Why does Object.opEquals return int

[Kristian Kilpi]

On Mon, 13 Nov 2006 20:16:12 +0200, Bill Baxter <wbaxter at gmail.com> wrote:

> Bruno Medeiros wrote:
>> Stewart Gordon wrote:
>>
>>> Anders F Björklund wrote:
>>>
>>>> Kristian Kilpi wrote:
>>>>
>>>>> So the original question remains: why 'opEquals' returns int?
>>>>
>>>>
>>>> Walter says it is for performance reason, when e.g. sorting...
>>>>
>>>> http://www.digitalmars.com/d/archives/digitalmars/D/bugs/7933.html
>>>
>>>
>>> I'm still not convinced that there's any way that opEquals can be made  
>>> more efficient by returning int instead of bool.
>>>
>>> Stewart.
>>>
>>  Even more so due to the SETE instruction (which gcc uses) and makes  
>> converting to a bool after a comparison just as fast as getting an int.  
>> I wish Walter would comment on that, because, in the point that the  
>> discussion was left using a bool would be just as fast as an int, and I  
>> would like a lot of those functions like opEquals to return a bool.
>
> I think it was already pointed out that instruction count doesn't tell  
> you anything cycle counts.  SETE maybe one instruction, but that doesn't  
> necessarily mean it's any faster.  I may be.  I don't know.  Just it  
> isn't a given.  Also I you're free to make your own classes return bool  
> from opCmp, it's just Object opCmp that returns int.  And note that it's  
> only for _value_ comparison of objects.
>
> Personally I think Object.opCmp returning int is an oddity, but it pales  
> in comparison with the mixins/imports problem, the ambiguity of auto,  
> and the major bugs left in variadic templates.
>
> --bb

You're absolutely right. :) I think, also, that template/mixin/import  
problems should be resolved as soon as possible. Then bugs (e.g. in  
varidiac templates) should be fixed.

(BTW, you were referring 'opCmp' instead of 'opEquals'. And yes,  
instruction count tells nothing, it's the cycle counts that, well, counts.  
And I'd imagine that converting an int to bool should take relative small  
amount of cycles.)